The Yankees’ bullpen has been a big reason why they are where they are right now, at 25-14 and in first place after winning seven of their last eight.

After Tuesday night’s 4-3 win over the Mariners (my story on their 11th comeback win and surviving a King Felix start), the relievers hadn’t given up a run over their last nine games, covering 23 2/3 innings. Their combined ERA for May is 0.77 (three earned runs in 35 innings). The group has 36 strikeouts and seven walks to show for this stretch.

“It’s unbelievable,” CC Sabathia said. “We knew coming into the season that would be one of the strong points on the team. They haven’t disappointed.”

Shawn Kelley came in for Sabathia Tuesday night with runners at the corners and one gone in the seventh. Strikeout. Line out. Inning over. The righty has fanned seven of the last nine batters he has faced. He owns 25 Ks in 15 1/3 innings this season.

Mariano Rivera came on for the ninth. Fly ball. Fly ball. K. Game over. The 43-year-old greatest-of-all-time closer is off to a 16-for-16 start on saves after 39 games. It’s the fewest number of team games he has needed to reach 16 saves. The latest save made him 35 for his last 35 at home and 17 for 17 at home against Seattle in his career.

Overall, the Yankees are now 8-2 in one-run games.

“I think winning those games are extremely important,” Joe Girardi said. “Those games can have a real effect when you start losing them.

“Our bullpen has done a great job for us this year. We’ve had a lot of close games. Mo has 16 saves already. That’s quite a pace that he’s on. We haven’t had to use him in games where we’re not winning because he’s got so many opportunities. The ones that you’re ahead, you need to win. If you want to play in the month of October, you have to win those games.”